New temperature controlling mechanism for thermal metrology regulation at NIS-Egypt

摘要

Thermal metrology laboratory at the National Institute of Standards (NIS-Egypt) has been working for the last four years to realize the International Temperature Scale 1990 in low-temperature ranges. It is required to develop a temperature controlling system to regulate the temperature precisely. Two mathematical algorithm techniques are considered to stabilize the temperature of an evacuated copper cylinder that is located inside an isolated calorimeter, and the normal PI and modified fractional PI controls have been designed and developed based on Laboratory Virtual Instrument for Engineering Workbench (LabVIEW(A (R))) software. The new improved fractional PI controlling mechanism has showed stability better than 3 +/- 1 mK in temperature and 45 +/- 1 min in time performances. The estimated uncertainty related to the measurements has been improved up to +/- 0.32 mK.